Both of those tend to have lifetime warranties on the cartridge, if you call them, they may send you new ones. Some of the faucets and things like shower valves have inlet filter screens either inside, or in the case of the vanity faucet maybe part of the supply hose...so, take the hot water hose off the vanity and see if it flow well and if you can flush anything out. While it will make a mess, with the cartridge out, you can turn the water back on with something over the opening to direct (as much as you can!) back into the sink (or shower). Long term, you should budget for a repipe, as galvanized piping only gets worse, never better. Rust clogging up things is the first step...eventually, enough rusts away that you end up with holes, which is much worse than low flow!
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013
Damn straight on the repipe, but I will try and coordinate that with the next time the tenant moves out.
I don't have time ti get a new cartridge in the mail.
I have a female tenant who wants to take a shower!
I hate it under the sink, but thats where I need to go.
I guess I just need to pull the shower catridge and see whats what.
would it be a bad idea to so the cartridge in vinegar or CLR for sediment removal?